1. Field of the Invention
The present invention relates generally to flare gas burners, and more particularly, but not by way of limitation, to an improved shielded flare gas burner adapted to be connected to a flare gas conduit or stack.
2. Description of the Prior Art
Flares are commonly utilized for disposing of gases, both waste gases and gases flared as a result of equipment shut-downs, plant upsets, etc. The flared gases are burned by a flare burner either continuously or intermittently, and to insure that the flared gases are ignited and that the burning thereof is maintained, continuously burning pilot flames are generally provided at the flare gas burner.
Flare burners utilized for flaring gases which produce smoke when burned have in many cases included provision for injecting a smoke supressant such as steam or a steam-air mixture into the burning gases whereby smoke emissions therefrom are reduced or eliminated. The smoke suppressant can be injected from within the flare burner, but generally it has been found that for the most efficient and effective suppression, at least some of the suppressant should be injected into the burning zone from points around the periphery of the burner flare gas discharge end.
While a variety of flare gas burner designs and multiple burner arrangements have been developed and used heretofore, in applications where a high maximum flow rate of flare gas is to be handled by the flare, a single flare gas burner of relatively large diameter is often used. Unfortunately, most of such flares seldom, if ever, operate at the maximum flow condition, and consequently, the flares frequently handle gas flow rates which are only small fractions of the maximum. The low flow rates in combination with wind acting on the flare gas burner often cause internal and/or external burning which bring about the early failure of the burner.
Internal burning occurs as a result of wind blowing transversely to the longitudinal axis of a flare gas burner when a low rate of gas is flowing through the burner. The wind causes a low pressure zone to develop within the open discharge end of the burner which in turn causes air to be drawn into the burner. As the air and gas mix within the burner, internal burning takes place. Such internal burning can cause flame impingement and excessive heat damage to the internal walls of the burner which can and usually does drastically shorten the life of the burner.
While increased gas flow rates overcome the problem with internal burning, the combination of a gas flow rate which is still less than maximum and wind can bring about an undesirable condition of external burning. That is, as wind strikes a flare gas burner, a high pressure zone is developed on the windward side and a low pressure zone is developed on the leeward side. At certain less than maximum flow rates of gas through the flare gas burner, the low pressure zone created by the wind and the wind force against the flame above the burner cause a portion of the flame to move or to be pulled into the low pressure zone on the leeward side of the flare burner. This in turn brings about flame impingement and excessive heat damage to wall portions of the burner and its appurtenances.
Low pressure zones which promote external burning are also readily formed by wind acting on the portions of flare burners which extend outwardly from the external sides of the burners such as pilot flame burners and associated fuel gas conduits, ignitor apparatus, smoke suppressant nozzles and supply conduits and the like. External burning in such low pressure zones brings about damage to the burner as well as to the conduits and other protruding portions thereof.
By the present invention, an improved flare gas burner is provided which is shielded from heat and flare impingement damage brought about by internal and/or external burning thereby significantly increasing the operational life of the burner.